1. Field of the Invention
The present invention relates to an ink ribbon cassette to be attached to a printer and a printer to which an ink ribbon cassette can be attached.
2. Description of the Related Art
A dye sublimation printer prints images by bringing a recording medium such as a sheet into pressure contact with an ink ribbon by use of a thermal head and a platen roller and then energizing the thermal head to cause heating elements on the thermal head to generate heat so that a dye applied to the ink ribbon sublimates to transfer onto the sheet.
To facilitate attachment or removal of the ink ribbon to or from a printer body, a cylindrical supply bobbin around which the ink ribbon is wound and a cylindrical winding bobbin are contained in an ink ribbon cassette. In the ink ribbon cassette, the supply bobbin and the winding bobbin are rotatably held. When the ink ribbon cassette is attached to the printer body, the thermal head is positioned between the supply bobbin and the winding bobbin. With the ink ribbon and the sheet being overlapped, the thermal head is brought into pressure contact with the platen roller and driven to print images.
Before the ink ribbon cassette is attached to the printer body for use, external vibrations may be applied to the rink ribbon cassette due to transportation or the like. The vibrations applied to the ink ribbon cassette can cause the ink ribbon wound around the supply bobbin or the winding bobbin to loosen and be pulled out of the ink ribbon cassette. This necessitates preventing the supply bobbin and the winding bobbin in the ink ribbon cassette from rotating when the ink ribbon cassette is not attached to the printer body.
Japanese Patent Application Laid-Open No. 2001-205881 discusses an ink ribbon cassette that regulates rotation of a supply bobbin and a winding bobbin by engaging projecting portions of inner walls of the ink ribbon cassette with depressed portions of end surface portions of the supply bobbin and the winding bobbin. In Japanese Patent Application Laid-Open No. 2001-205881, a mold piece provided in the ink ribbon cassette biases the supply bobbin and the winding bobbin in an axial direction so that the depressed portions are engaged with the projecting portions to regulate the rotation of the supply bobbin and the winding bobbin. When the ink ribbon cassette is in use, the supply bobbin and the winding bobbin are pressed in the axial direction to release the regulation of the rotation.
In the conventional technique discussed in Japanese Patent Application Laid-Open No. 2001-205881, however, since the supply bobbin and the winding bobbin are slid by a resin spring such as the mold piece, if the volume of the ink ribbon wound around the bobbins increases to increase the weight of the ink ribbon, the load applied to the resin spring increases. This can easily cause the resin spring to be damaged or distorted, and necessitates a mold with greater strength.
Furthermore, since the supply bobbin and the winding bobbin around which the ink ribbon is wound are moved by sliding, the ink ribbon can be wrinkled, and the wrinkles can affect the printing.